Digital projection systems or devices are frequently used to display a still or video image. Viewers evaluate digital projection systems based on many criteria such as image size, color purity, brightness, resolution, and contrast ratio. Contrast ratio, or the difference in brightness between the lightest and darkest tones in the displayed image, is a particularly important metric in many display markets.
One popular class of digital projection systems is a front projection system. A front projection system projects an image onto a reflective screen which displays the image. Front projection systems are advantageous in many different settings because of their size, cost, and ease of use.
However, front projection systems are generally only suited for relatively dark rooms because front projection screens indiscriminately reflect all light incident to its surface with equal efficiency. Light from the projector can be diluted by light from room lights, windows, pixel to pixel interference, and/or any other ambient light. Thus, ambient light limits the effective contrast ratio of many front projector systems to undesirably low levels.